suggested_users.rb

class SuggestedUsers
  attr_reader :user, :options

  def initialize(user, options = nil)
    @user = user
    @options = options || {}
  end

  def suggested_users
    User.joins('JOIN follows as follows_follows ON follows_follows.followee_id = users.id')
        .where('follows_follows.followee_id NOT IN (SELECT followee_id FROM follows WHERE follower_id = :user_id)', user_id: user.id)
        .where('follows_follows.follower_id IN (SELECT followee_id FROM follows WHERE follower_id = :user_id)', user_id: user.id)
        .where('follows_follows.followee_id <> :user_id', user_id: user.id)
        .order('users.id DESC')
        .limit(limit).uniq
  end
  alias_method :all, :suggested_users

  def limit
    options.fetch(:limit, 50)
  end
end